#include<bits/stdc++.h>
using namespace std;

void multi(vector<int> &v, int j) {
	int i;
    for(i = 0; i < v.size(); ++i) {
        v[i] *= j;
    }
    for(i = 0; i < v.size()-1; ++i) {
    	if(v[i] >= 10) v[i+1] += v[i] / 10, v[i] %= 10;
	}
	while(v[i] >= 10) {
		v.push_back(v[i] / 10);
		v[i] %= 10;
	}
	while(v.back() == 0) v.pop_back();
    return;
}

void add(vector<int> &s, vector<int> t) {
	vector<int> c;
	c.clear();
	int i;
	for(i = 0; i < s.size() || i < t.size(); ++i) {
		if(i < s.size()) {
			if(i == c.size() - 1) c[i] += s[i];
			else c.push_back(s[i]);
		}
		if(i < t.size()) {
			if(i == c.size()) c.push_back(t[i]);
			else c[i] += t[i];
		}
		if(c[i] >= 10) {
			c.push_back(c[i] / 10);
			c[i] %= 10;
		}
	}
	if(c[i] >= 10) {
		c.push_back(c[i] / 10);
		c[i] %= 10;
	}
	while(c.back() == 0) c.pop_back();
	s.swap(c);
	return;
}

int main() {
    vector<int> s;
    int n;
    s.clear();
    s.push_back(0);
    cin >> n;
    for(int i = 1; i <= n; ++i) {
        vector<int> t;
        t.clear();
        t.push_back(1);
        for(int j = i; j >= 1; --j) {
            multi(t, j);
            /*
            cout << "t:";
    		for(int i = t.size() - 1; i >= 0; --i) {
    			cout << t[i];
			}
			cout << " j:" << j << endl;
			*/
        }
     	add(s, t);
     	/*
     	cout << "s:";
     	for(int i = s.size() - 1; i >= 0; --i) {
    		cout << s[i];
		}
		cout << endl;
		*/
    }
    for(int i = s.size() - 1; i >= 0; --i) {
    	cout << s[i];
	}
    return 0;
}

第一个评测没问题，但本地有时候是833(正确)，有时候千位是1，百位1到9随机变化